The of the proposed research is to understand the processing of emotion by the brain. The experiments are specifically concerned with the mechanisms by which insignificant events in the environment acquire salience as emotional signals. Previously, we demonstrated that a specific subcortical pathway, the geniculo- amygdala projection system, mediates the classical conditioning of fear responses to acoustic stimuli. In the present series of experiments we seek to extend these observations. Three projects are planned. Project 1 is concerned with the local mechanisms in the medial geniculate body and amygdala which mediate fear conditioning. The aims are to: (a) identify the precise anatomical location and topographic organization of the cells of origin and termination of the geniculo-amygdala projection; (b) determine whether lesions of the cells of origin and termination of the pathway disrupt fear conditioning; (c) characterize the sensory processing functions of the geniculo-amygdala projection using electrophysiological goal of Project 2 is to determine processing limits of the geniculo-amygdala projection by identifying aversive classical conditioning tasks which require the integrity of the auditory cortex. In these experiments animals with lesions of the auditory cortex will be conditioned using stimuli which must be discriminated on the basis of various sensory/perceptual properties. Project 3 then examines whether connections between the auditory cortex and the amygdala mediate emotional conditioning in training situations which require the auditory cortex. The aims are to: (a) localize the auditory receptive cortex using physiological mapping techniques; (b) identify pathways connecting acoustically responsive areas of the cortex with the amygdala; and (c) determine whether interruption of these pathways disrupts the conditioning of emotional responses which are dependent upon the auditory cortex. Together, the various experiments will individually and collectively to emotional information processing.